Towards predictive modeling of near-edge structures in electron energy-loss spectra of AlN-based ternary alloys

Abstract

Although the analysis of electron energy loss near-edge structure provides a tool for experimentally probing the density of unoccupied states, a detailed comparison with simulations is necessary in order to understand the origin of individual peaks. This paper presents a density functional theory based technique for predicting the N K edge for ternary (quasibinary) nitrogen alloys by adopting a core hole approach, a methodology that has been successful for binary nitride compounds. It is demonstrated that by using the spectra of binary compounds for optimizing the core hole charge ($0.35 e$ for cubic Ti${}_{1\ensuremath{-}x}$Al${}_{x}$N and $0.45 e$ for wurtzite Al${}_{x}$Ga${}_{1\ensuremath{-}x}$N), the predicted spectra evolutions of the ternary alloys agree well with the experiments. The spectral features are subsequently discussed in terms of the electronic structure and bonding of the alloys.